A comparison of antigen-induced and calcium ionophore A23187 induced contraction of isolated guinea pig trachea.
Ovalbumin (OA) and the calcium ionophore A23187 induced a dose-dependent contraction of guinea pig tracheal strips. The OA-induced contraction (of sensitized trachea) consisted of an initial peak concentration, maximal between 5 and 10 min, followed by a very gradual decline from the peak. On the other hand, A23187 induced a sustained contraction of the trachea with a more gradual onset. Both antigen- and A23187-induced contractions required the presence of extracellular calcium. The response was not reduced by delaying (up to 10 min) the addition of calcium, suggesting that the mechanism of antigen-induced contraction differs from that of antigen-induced histamine secretion from rat mast cells and human basophils. The 1st min of the OA-induced contraction was inhibited significantly by mepyramine (10(-5) M) suggesting that histamine contributed to the contraction at this time point. In contrast, A23187-induced contraction was unaffected by mepyramine. On the other hand, both the A23187-induced contraction and the prolonged phase of the OA-induced contraction were enhanced by indomethacin, a cyclooxygenase inhibitor, and inhibited by phenidone, a cyclooxygenase-lipoxygenase inhibitor. This suggests that a product of the lipoxygenase pathway of arachidonic acid metabolism contributes to OA- and A23187-induced contraction of the guinea pig trachea.
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000941:Antigens / Q000276:immunology*; D000001:Calcimycin / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology; D003286:Contracture / Q000139:chemically induced*; D006168:Guinea Pigs; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D010047:Ovalbumin / Q000276:immunology*; D011720:Pyrazoles / Q000494:pharmacology; D011738:Pyrilamine / Q000494:pharmacology; D013997:Time Factors; D014132:Trachea / Q000187:drug effects* / Q000276:immunology
D000900:Anti-Bacterial Agents; D000941:Antigens; D011720:Pyrazoles; D000001:Calcimycin; D010047:Ovalbumin; C015429:phenidone; D011738:Pyrilamine; D002118:Calcium; D007213:Indomethacin